This application claims Paris Convention priority of DE 101 43 990.3 filed Sep. 7, 2001 the complete disclosure of which is hereby incorporated by reference.
The invention concerns an X-ray analysis apparatus for investigating sample materials having a device for automatic exchange of the samples which comprises a gripping device for precise removal and return of any desired sample from and back to a deposition position and for transferral into a transfer and/or measuring position, wherein at least some of the samples are surrounded, in the peripheral direction, by a sample holder.
An X-ray analysis apparatus of this type is known e.g. from the company leaflet xe2x80x9cSPECTROMETRY SOLUTIONS; S4 EXPLORERxe2x80x9d, Bruker AXS Analytical X-Ray Systems GmbH, 2001.
This document provides a detailed description of the functional principles of an arrangement of this type. Such X-ray analysis apparatus are used in laboratories and research institutes for rapid, routine, and non-destructive analyses of the most differing of sample materials. X-ray fluorescence methods, X-ray diffractometry, or other X-ray analysis methods can be used for examining the material samples. The material samples may be massive solid bodies, powder, or liquid samples disposed in appropriate sample containers.
Analysis devices of this type are provided for routine, rapid examination of a large number of samples. For this reason, an automatic exchange device must be provided for transporting, within the device, each of a plurality of samples to be examined. The known devices comprise a sample table for receiving the samples which is immovably fixed in the apparatus as e.g. described in the above-cited company leaflet. This sample table has openings defining an mxc3x97n matrix for inserting the different samples or sample containers. These are filled manually with the different samples according to a plan determined by the user before starting a measuring series which subsequently runs automatically without further manual influence on the part of the user.
Towards this end, the X-ray analysis apparatus comprises a gripping device for precise removal of any desired sample from one of the depositing positions, transfer into a transfer or measuring position and for return back into the depositing position. To be able to address all positions on the rigid, rectangular sample table, the gripping device drive mechanics must be relatively complicated. The gripping robot must be movable in both the x and y directions.
The samples or sample containers of an X-ray analysis apparatus of this type are usually dimensioned in the z direction to end flush with the upper edge of the sample holder where the gripping device engages (see e.g. DE 198 51 501 C1). The sample-sided part of the gripping device thereby abuts the upper edge of the sample and of the sample holder during the gripping process.
Samples which extend in the z direction, e.g. containers with sample liquid or rod-shaped solid body samples, cannot be automatically moved with the gripping device of this system. Up to now, such samples had to be individually, manually inserted into the measuring position. Routine investigation of a plurality of samples has not been previously possible with such elongated samples using the conventional arrangement of gripping device and sample holder.
In contrast thereto, it is the underlying purpose of the invention to propose an X-ray analysis apparatus having the above-mentioned features which also permits automatic processing of a plurality of samples in an X-ray analysis device of this type using as simple and as few technical means as possible and with samples of considerable extension in the z direction.
This object is achieved in accordance with the invention in a surprisingly simple and effective fashion in that the samples or containers holding the samples project past the sample holder in the direction of a vertical z direction extending perpendicular to the horizontal x-y plane, wherein the gripping device is disposed and structured on a side of the sample to surround the parts of a sample or of a sample container projecting, in the z direction, past the sample holder in an operating position to grasp the sample holder.
Modification of an X-ray analysis apparatus of this type is thereby possible with means which are technically easy to realize to facilitate processing of samples extended in the z direction, e.g. liquid containers. This design also facilitates loading and unloading of a sample holder with such extended samples. Moreover, this grasping system can easily grasp conventional samples thereby allowing universal use of the invention for the most differing types of samples. Previously, difficult special solutions had to be found for samples extended in the z direction. The above embodiment of the invention permits standardization of a very simple sample holder and use thereof at little expense.
In a particularly preferred embodiment of the invention, the sample holder comprises one (or several) holding section(s) disposed adjacent to the bottom-sided end of the sample or of a sample container to engage behind the sample or the container holding the sample in a plane which is parallel to the x-y plane for forming a mechanical stop in the z direction for the sample or the sample container. This further facilitates loading the sample holder with the sample to obtain a defined, final position in the z direction.
The holding section is preferably annular to provide full peripheral contact of the sample when fitting into the sample holder. For samples with flat bottoms, surface contact is thereby achieved. For samples with a bulged bottom, e.g. a test tube, at least circular contact is provided to guarantee a defined z position of the sample relative to the sample holder.
The sample holder usually surrounds the sample annularly, preferably circularly, on its side facing the gripping device during operation. The sample or the sample container can then either be inserted or pressed into the sample holder ring.
In a further development of the invention, the sample holder comprises several parallel rods extending in the z direction which surround the sample in the peripheral direction on its side facing the gripping device during operation. This facilitates centering of the sample and extension of the rods in the z direction also provides a certain flexibility for deflection in the x-y plane during insertion of the sample to prevent damage to the sample due to excessive loading during pressing into the sample holder.
A further development is also advantageous wherein the parallel rods are disposed on the upper side of the annular holding section facing the gripping device during operation. The sample holder is thereby formed by the annular holding section and the rods disposed thereon which extend in the z direction.
Instead of the annular structure on the side of the sample, in embodiments of the invention, the gripping device can comprise at least three parallel rods which are preferably distributed uniformly about the periphery of the sample to be held and which extend in the z direction.
In embodiments of the invention, the gripping device can be operated mechanically. Although a gripping robot of this type is simple and inexpensive to manufacture, it is not very compact and does require significant amounts of space. In particular, relatively large amounts of space are usually required in the horizontal x-y plane for a mechanical gripping process. The depositing positions of the samples on the sample table in these embodiments must consequently have corresponding mutual separations to ensure safe gripping of the samples in the sample holder without contacting neighboring samples.
Alternatively or additionally, the gripping device can be operated pneumatically, preferably through suctioning the sample holders by underpressure. A pneumatically actuated mechanical gripper is also possible with which the pneumatic gripping suctioning process must be carried out only at locations with particularly little space. In this case, the pneumatic device may serve both parts of the gripping system.
In a further development of this embodiment, the gripping device comprises rod-shaped gripping elements disposed on the side of the sample (as in an above-mentioned embodiment), wherein at least some of the parallel rods extending in the z direction can define suction nozzles for suctioning parts of the sample holder. In any case, an arrangement of this type requires considerably less space than a mechanical gripping arrangement since the parallel rods must not deflect in the x-y plane during the gripping process but can be rigidly lowered onto the sample holder in the z direction.
Embodiments of the invention are particularly preferred with which the gripping device is operated magnetically. Although a magnetic means of this type is usually more expensive than a mechanical means, it can be designed much more compactly.
In most of these embodiments, the gripping device is an electromagnet which can be externally controlled with electrical currents for activating and deactivating the gripping process.
In other further developments of this embodiment, the gripping device can have permanent magnetic sections on its side facing the sample holder during operation. A magnetic gripping device of this type is somewhat less demanding than an electromagnet, however a device for mechanical displacement of the permanent magnetic sections in the z direction must be provided for separating the grasped sample when depositing into the respective target position.
In a particularly preferred further development of the invention, the sample holder is formed at least partially of magnetizable, preferably ferromagnetic material on its side facing the gripping device during operation such that attraction and gripping thereof by means of a magnetic gripping device is particularly simple.
Finally, another advantageous further development of the invention provides that the annular holding section consists of plastic material into which ferromagnetic rods, extending in the z direction, are inserted on the side of the sample holder facing the gripping device during operation between which the sample or a container containing the sample can be received. An arrangement of this type can be produced and handled at relatively low cost.
A sample holder having the above-described properties and a gripping device with the inventive modifications for use in an X-ray analysis apparatus of the inventive type are also within the scope of the invention.
Further advantages can be extracted from the drawings and the description. The features mentioned above and below can be used in accordance with the invention either individually or collectively in any arbitrary combination. The embodiments shown and described are not to be understood as exhaustive enumeration, rather have exemplary character for describing the invention.
The invention is shown in the drawings and is explained in more detail by means of embodiments.